High-Directivity Antenna Array Based on Artificial Electromagnetic Metamaterials with Low Refractive Index

Abstract

Planar metamaterials (MTMs) with low refractive index are proposed as a cover in a high-gain patch antenna array configuration. This MTMs array antenna has the following features: the number of array elements significantly decreases compared with the conventional array; the elements spacing is larger than a wave length by far; the feeding network is simpler. MTMs are made of two layers of periodic square metallic grids and placed above the feeding array. With the same aperture size, the directivity of MTMs-cover antenna array is higher than the conventional antenna array. The simulation results show that an array of 2 × 2 patch elements integrated with MTMs yields about 26 dB of directivity which is higher than that of conventional 8 × 8 patch array. Furthermore, on the condition of the same aperture size, an array patch with 4 × 4 elements integrated with the MTMs-cover has an equivalent gain compared with the conventional patch array with 16 × 16 array elements. Obviously, the former has a simpler feeding network and higher aperture efficiency. The experimental work has verified that the 2 × 2 array case and the measured results have good agreement with the simulation.

Double Layer Metamaterial Superstrate for Performance Enhancement of a Microstrip Patch Antenna

“…These new kinds of artificial materials, constructed from periodic unit structures that are compactly crowded into an effective material, open the way to observe some exotic properties that are impossible to achieve with natural materials. Many research works have been achieved in obtaining the high directivity of antenna by using metamaterial structures [5][6][7][8][9][10][11][12]. MTMs can be fabricated through various ways such as photonic crystal [9], electromagnetic band gap (EBG) structure, frequency selective surface (FSS) [10][11], and other periodic artificial material which can be designed to have a low ∕ zero refractive index [12][13].Particularly, negative refractive index zero or near zero index metamaterial, and furthermore lead to potential applications, many of which were considered difficult in the past.…”

A bi-functional illusion device based on transformation optics

“…In this regard, the mapping technique of transformation from virtual-space to physical-space using coordinate-transformation recipe is very important in achieving the constitutive parameters for the designing of optical devices, i.e., EM field, source transformation, multi-beams, field-concentrators and rotators, isotropic emissions, and invisibility cloaks etc. Similarly, directive antennas have been introduced employing the TO to achieve high-directivity from the smaller-sized antenna [36][37][38][39][40][41]. Overall, the TO technique is useful in constructing the conceptual devices, whereas the hurdle of complex constitutive parameters can be minimized by achieving homogeneous-materials using linear coordinate transformation method [19,39,42].…”

“…Therefore, the mapping methodology of virtual to physical space conversion using coordinate transformation theory plays an important role in achieving the material properties for the construction of various optical devices, such as invisibility cloaks, EM fieldrotators, field-concentrators, source transformation, multibeams, and isotropic emissions . In addition, the employment of the mapping technique in TO has opened doors for directive antennas to fulfil the demands of modern telecommunication systems to attain the high directivity from the smaller-sized radiator [36][37][38][39][40][41]. Thus, the rapid development in TO provokes the construction of more conceptual devices, while the barrier of complex material properties can be addressed by obtaining homogeneous materials using a linear coordinate transformation method [19,39,42].…”